Throughout its long history cannabis has mostly been used for medicinal purposes and it wasn't until the 20th Century that it became the world's most widely used illegal recreational drug.
It is believed that cannabis may treat a variety of illness
More recently medical researchers have begun to investigate cannabis' potential as a medicine once again.
Although cannabis' illegal status has made research more difficult, scientists have found that it can have an impact on the symptoms of many diseases, including asthma, glaucoma and muscle spasms, as well as loss of appetite and nausea due to AIDS and chemotherapy treatment.
In most countries around the world cannabis is still listed as a Schedule I drug: "unsafe, highly subject to abuse, and possessing no medical value."
However, Canada became the first country to adopt a system allowing the medicinal use of marijuana in July 2001.
In 2003 Holland became the first country in the world to offer cannabis as a medicine.
The Dutch Ministry of Health will provide cannabis to people suffering from Multiple Sclerosis, cancer, HIV/Aids, Tourette's syndrome and those suffering from long term pain.
The Medical Research Council conducted the first trials In the UK of cannabis as a potential medicine.
Two hundred Multiple Sclerosis (MS) sufferers were recruited to see what impact cannabis had on their symptoms.
Following on from this, British firm, GW Pharmaceuticals began clinical trials of its own cannabis medicine.
Sativex contains THC (tetrahydrocannabinol) and CBD (cannabidiol) in equal measure and is delivered via a vaopouriser and is designed to alleviate the symptoms of MS.
In April 2005 Sativex became the first cannabis medicine to be licensed anywhere in the world after it won approval in Canada.
GW has also applied for a license in UK and is awaiting approval.